US11754679B2 - Electro-optical distance meter - Google Patents
Electro-optical distance meter Download PDFInfo
- Publication number
- US11754679B2 US11754679B2 US16/365,523 US201916365523A US11754679B2 US 11754679 B2 US11754679 B2 US 11754679B2 US 201916365523 A US201916365523 A US 201916365523A US 11754679 B2 US11754679 B2 US 11754679B2
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- light
- optical path
- liquid
- electro
- shutter
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
- G01S7/4818—Constructional features, e.g. arrangements of optical elements using optical fibres
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
- G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/481—Constructional features, e.g. arrangements of optical elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
- G02B26/004—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid
- G02B26/005—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid based on electrowetting
Definitions
- Electro-optical distance meters have recently been used to make surveys necessary for construction or map production.
- an electro-optical distance meter measures a distance by irradiating a target with measurement light emitted from a light source, receiving the measurement light reflected from the target with a light receiving unit, and electronically analyzing the received light.
- the electro-optical distance meter changes the intensity of the measurement light (i.e., modulates the measurement light), and measures a phase difference that indicates how much the waveform of the reflected light returning to the light receiving unit deviates from the waveform of the outgoing light from a light emitter.
- the measurement light is modulated through modulation of a light source such as a lamp based on a reference signal.
- the measurement light is subjected to phase shift due to a change in output caused by, for example, a thermal drift. In such a case, the measurement light cannot provide correct measurement data.
- the electro-optical distance meter includes an internal optical path for use in measurement based on reference light so as to correct a measurement value.
- An electro-optical distance meter including such a shutter mechanism to constantly conduct correct distance measurement is described in, for example, Japanese Patent No. 4707365.
- the electro-optical distance meter disclosed in Japanese Patent No. 4707365 includes, for example, a mechanical shutter mechanism (mechanical shutter) to switch between the external optical path and the internal optical path.
- a mechanical shutter to measure a distance as described in Japanese Patent No. 4707365 leads to a loss of measurement time in switching between the measurement light and the reference light. This is because opening and closing the mechanical shutter takes time, and the measurement data cannot be acquired until the shutter completes its opening and closing operations.
- Embodiments of the present disclosure have been made in view of the foregoing background.
- An electro-optical distance meter described in the present disclosure can ensure a longer measurement time and higher operational reliability.
- the electro-optical distance meter according to the claimed embodiments can provide a longer measurement time and higher operational reliability.
- FIG. 1 is a schematic diagram illustrating a general configuration of an electro-optical distance meter according to an embodiment of the present disclosure
- FIG. 4 is a schematic diagram illustrating a general configuration of an electro-optical distance meter including liquid shutters according to a modification of the embodiment.
- the light transmitting optical system 3 includes a first mirror 20 and a second mirror 21 .
- the first mirror 20 and the second mirror 21 reflect the measurement light emitted from the light source 10 .
- the light is then transmitted from the electro-optical distance meter 1 to a target T.
- the target T may be a retroreflector such as a prism, or any other objects that reflect a laser beam.
- the light receiving optical system 4 includes an objective lens 30 and a third mirror 31 .
- the objective lens 30 collects the measurement light reflected from the target T and the third mirror 31 reflects the collected light to a detector 40 , which will be described below.
- the control unit 5 includes the detector 40 , a calculator 41 , and a driver 42 .
- the driver 42 is connected to the calculator 41 and a liquid shutter 50 , which will be described below.
- the driver 42 drives the liquid shutter 50 while being under the control of the calculator 41 .
- the optical path switching unit 6 includes the liquid shutter 50 , a semitransparent mirror 51 , a fourth mirror 52 , and an optical fiber 53 .
- the semitransparent mirror 51 reflects part of the light emitted from the light source 10 to the fourth mirror 52 as reference light.
- the fourth mirror 52 reflects the reference light to the optical fiber 53 through the liquid shutter 50 .
- the optical fiber 53 guides the reference light to the detector 40 .
- the light-transmitting region 50 a of the liquid shutter 50 is positioned across the internal optical path L 2 and the light-blocking region 50 b is positioned across the external optical path L 1 , the light from the light source 10 travels, as the reference light, through the optical path switching unit 6 , and then is received by the detector 40 .
- the calculator 41 measures a distance based on the reference light in the same manner as the distance measurement based on the measurement light passing through the external optical path L 1 , so that the calculator 41 calculates an error arising in the electro-optical distance meter 1 at this time.
- the calculator 41 transmits a switching signal for switching the external optical path L 1 and the internal optical path L 2 to the driver 42 so as to switch the liquid shutter 50 , and calibrates the error based on the reference light.
- the calibration timing is determined in accordance with, for example, a change in temperature or how much time has passed since the last calibration.
- FIG. 2 is a flowchart illustrating a distance measurement control routine performed by the control unit 5 . It is described next how the distance measurement control is carried out according to this embodiment, with reference to the flowchart.
- Step S 1 the control unit 5 starts the distance measurement operation of the electro-optical distance meter 1 .
- the driver 42 performs switching to position the light-blocking region 50 b of the liquid shutter 50 across the external optical path L 1 . Accordingly, the light from the light source 10 passes through the light-transmitting region 50 a of the liquid shutter 50 as the reference light, and travels through the internal optical path L 2 to enter the detector 40 .
- Step S 3 the driver 42 performs switching to position the light-blocking region 50 b of the liquid shutter 50 across the internal optical path L 2 . Accordingly, the light from the light source 10 passes through the light-transmitting region 50 a of the liquid shutter 50 as the measurement light, and travels through the external optical path L 1 to enter the detector 40 .
- Step S 4 the calculator 41 measures a distance based on the measurement light received by the detector 40 .
- Step S 7 If yes in Step S 7 , that is, for example, if a predetermined time has passed since the last calibration or if the temperature has changed by predetermined degrees or more, the routine is returned to Step S 1 where switching of the liquid shutter 50 is performed again.
- the calculator 41 then acquires a measurement value based on the reference light again.
- the calculator 41 acquires, as appropriate, measurement values based on the reference light, and continues to acquire measurement values based on the measurement light.
- FIG. 3 illustrates a comparison between the measurement time of the electro-optical distance meter according to this embodiment and that of an electro-optical distance meter including a mechanical shutter. With reference to FIG. 3 , effects of this embodiment will be described.
- the upper diagram of FIG. 3 is a measurement time chart of the electro-optical distance meter 1 according to this embodiment
- the lower diagram is a measurement time chart of the known electro-optical distance meter including a mechanical shutter.
- the electro-optical distance meter 1 according to this embodiment and the known electro-optical distance meter both take the same measurement procedure. Both measure a distance based on the measurement light (measurement light-based measurement), switch the shutter at the same timing, and then measure a distance based on the reference light (reference light-based measurement), and switch the shutter again to return to the measurement light-based measurement.
- the known electro-optical distance meter which has the mechanical shutter, spends time equivalent to about one cycle of the measurement light-based measurement on a single switching operation of the mechanical shutter. In addition to the switching operations, the reference light-based measurement takes time. As a result, the known electro-optical distance meter suffers a measurement time loss equivalent to about three cycles of time for the measurement light-based measurement.
- the electro-optical distance meter 1 which has the liquid shutter 50 comprised of an electrowetting device, spends much less than one cycle time of the measurement light-based measurement on switching the liquid shutter.
- the measurement time loss is less than two cycles of time for the measurement light-based measurement.
- the electro-optical distance meter 1 since the electro-optical distance meter 1 according to this embodiment includes the liquid shutter 50 to switch back and forth between the external optical path L 1 and the internal optical path L 2 , the electro-optical distance meter 1 can reliably shorten the time period needed for switching the shutter, as compared to an electro-optical distance meter having a mechanical shutter. This feature can reduce the loss of measurement time, and can ensure a longer time for the measurement light-based measurement.
- the liquid shutter 50 which is configured to move the liquid in response to application of voltage, is less likely to suffer from mechanical friction and less likely to be damaged by an external impact. Using the liquid shutter 50 can reduce the chances of failures and increase the operational reliability of the electro-optical distance meter.
- liquid shutter allows the external optical path L 1 and the internal optical path L 2 to be arranged at a smaller spacing from each other than a case where the mechanical shutter is used. This feature enables the shitter device to have a small size in accordance with the beam size of the measurement light. As a result, electro-optical distance meter can be reduced in size.
- the liquid shutter 50 according to the embodiment described above is comprised of a single electrowetting device, but the number of electrowetting devices forming the liquid shutter 50 is not limited to this.
- FIG. 4 illustrates a general configuration of an electro-optical distance meter including liquid shutters according to a modification of the embodiment.
- Components of the modification similar to those of the embodiment described above are denoted by the same reference characters, and detailed description thereof is omitted herein.
- this electro-optical distance meter 1 ′ includes, in an optical path switching unit 6 ′, two electrowetting devices that constitute a first liquid shutter 60 and a second liquid shutter 61 as the liquid shutters of this modification.
- the first liquid shutter 60 and the second liquid shutter 61 are spaced apart from each other such that the first liquid shutter 60 is disposed across the external optical path L 1 and the second liquid shutter 61 is disposed across the internal optical path L 2 .
- the first liquid shutter 60 and the second liquid shutter 61 are each a smaller version of the liquid shutter 50 of the embodiment described above.
- the first liquid shutter 60 and the second liquid shutter 61 have light-transmitting regions 60 b and 61 b , respectively, in one region, and have light-blocking regions 60 a and 61 a , respectively, in the other region.
- Each of the first and second liquid shutters 60 and 61 can cause the respective light-transmitting region and the respective light-blocking region to switch places in response to application of voltage by the driver 42 .
- the driver 42 switches the first liquid shutter 60 and the second liquid shutter 61 in conjunction with each other. Specifically, the first liquid shutter 60 and the second liquid shutter 61 are switched in a synchronized manner such that the first liquid shutter 60 transmits the light to the external optical path L 1 while the second liquid shutter 61 blocks the light to the internal optical path L 2 , or that the first liquid shutter 60 blocks the light to the external optical path L 1 while the second liquid shutter 61 transmits the light to the internal optical path L 2 .
- the electro-optical distance meter 1 ′ includes the liquid shutters 60 and 61 that are spaced apart from each other and switched in conjunction with each other.
- the liquid shutters 60 and 61 have a simple structure, thereby allowing for a flexible layout.
- the liquid shutters 60 and 61 can be switched instantaneously between a light-transmitting state and a light-blocking state.
- the electro-optical distance meter 1 ′ according to this modification also can ensure a longer measurement time and higher operational reliability in the same manner as the electro-optical distance meter according to the embodiment described above, and in addition, can increase the degree of freedom of design.
- the electro-optical distance meter to be used alone has been described as an example.
- the type of the electro-optical distance meter is not limited to this.
- the embodiment of the present disclosure can be applied to an electro-optical distance meter included in a total station.
- the total station can measure a distance using the electro-optical distance meter and can measure the horizontal angle and the vertical angle with respect to the collimation axis.
- the total station measures the position of an unmanned aerial vehicle (UAV) flying in the sky to take pictures for photogrammetry, while tracking the UAV If the total station can reduce loss of measurement time, the total station misses fewer pieces of positional information of the UAV and can carry out more precise photogrammetry.
- UAV unmanned aerial vehicle
- the embodiment of the present disclosure can be applied to an electro-optical distance meter implemented as a three-dimensional (3D) scanner.
- the 3D scanner includes Risley prisms to change the direction of a laser beam (measurement light) in any direction.
- the 3D scanner scans the laser beam over a target to acquire a three-dimensional point cloud.
- the 3D scanner misses fewer pieces of point cloud information and can efficiently increase the density of the point cloud and improve the scanning accuracy.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Computer Networks & Wireless Communication (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Electromagnetism (AREA)
- Optics & Photonics (AREA)
- Optical Radar Systems And Details Thereof (AREA)
Abstract
Description
Claims (5)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2018-061906 | 2018-03-28 | ||
JP2018061906A JP7084177B2 (en) | 2018-03-28 | 2018-03-28 | Laser rangefinder |
Publications (2)
Publication Number | Publication Date |
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US20190302233A1 US20190302233A1 (en) | 2019-10-03 |
US11754679B2 true US11754679B2 (en) | 2023-09-12 |
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US16/365,523 Active 2042-04-09 US11754679B2 (en) | 2018-03-28 | 2019-03-26 | Electro-optical distance meter |
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JP (1) | JP7084177B2 (en) |
Families Citing this family (2)
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JP2021085822A (en) * | 2019-11-29 | 2021-06-03 | ソニーセミコンダクタソリューションズ株式会社 | Ranging sensor, ranging system, and electronic device |
US11481236B1 (en) * | 2021-05-14 | 2022-10-25 | Slack Technologies, Llc | Collaboration hub for a group-based communication system |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04177195A (en) | 1990-11-09 | 1992-06-24 | Opt:Kk | Measuring distance with light wave and light wave distance meter |
US20050270672A1 (en) | 2002-09-19 | 2005-12-08 | Koninkjkle Phillips Electronics Nv. | Switchable optical element |
CA2555766A1 (en) * | 2005-09-30 | 2007-03-30 | Kabushiki Kaisha Topcon | Distance measuring device |
US20070188676A1 (en) | 2006-02-13 | 2007-08-16 | Samsung Electronics Co., Ltd., | Display device and a method thereof |
JP4707365B2 (en) | 2004-10-25 | 2011-06-22 | 株式会社 ソキア・トプコン | Light wave distance meter |
EP3447535A1 (en) * | 2017-08-24 | 2019-02-27 | Topcon Corporation | 3-dimensional measuring device |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2731565B2 (en) * | 1989-01-11 | 1998-03-25 | 松下電工株式会社 | Distance sensor |
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2018
- 2018-03-28 JP JP2018061906A patent/JP7084177B2/en active Active
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2019
- 2019-03-26 US US16/365,523 patent/US11754679B2/en active Active
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH04177195A (en) | 1990-11-09 | 1992-06-24 | Opt:Kk | Measuring distance with light wave and light wave distance meter |
US20050270672A1 (en) | 2002-09-19 | 2005-12-08 | Koninkjkle Phillips Electronics Nv. | Switchable optical element |
JP2006500614A (en) | 2002-09-19 | 2006-01-05 | コーニンクレッカ フィリップス エレクトロニクス エヌ ヴィ | Switchable optical components |
JP4707365B2 (en) | 2004-10-25 | 2011-06-22 | 株式会社 ソキア・トプコン | Light wave distance meter |
CA2555766A1 (en) * | 2005-09-30 | 2007-03-30 | Kabushiki Kaisha Topcon | Distance measuring device |
US20070188676A1 (en) | 2006-02-13 | 2007-08-16 | Samsung Electronics Co., Ltd., | Display device and a method thereof |
JP2007219510A (en) | 2006-02-13 | 2007-08-30 | Samsung Electronics Co Ltd | Display device |
EP3447535A1 (en) * | 2017-08-24 | 2019-02-27 | Topcon Corporation | 3-dimensional measuring device |
Non-Patent Citations (1)
Title |
---|
Notice of Reasons for Refusal dated Nov. 9, 2021, in connection with Japanese Patent Application No. 2018-061906, 6 pgs (including translation). |
Also Published As
Publication number | Publication date |
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JP7084177B2 (en) | 2022-06-14 |
US20190302233A1 (en) | 2019-10-03 |
JP2019174247A (en) | 2019-10-10 |
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